Piston pump



E. O. SUNDIN July 8, 1958 PISTON PUMP 4 Sheets-Sheet l Filed Oct. 4, 1955 July 8, 1958 E o, SUNDIN 2,842,068

PISTON PUMP Filed 001;. 4, 1955 4 Sheets-Sheet 2 E. O. SUNDIN July 8, 1958 PISTON PUMP 4 Sheets-Sheet 3 Filed 00T.. 4, 1955 .2m Vian Piuma H E w wwl Filed Oct. 4, 1955 4 Sheets-Sheet 4 Unit This invention relates to a piston pump comprising a block with borings or piston cylinders therein parallel to one another, which borings are arranged around the rotatably driven shaft of the pump, and which borings are parallel to said shaft and extend through the block of the pump. In each of these borings or piston cylinders two pistons are movable in opposite directions, the outer ends of the pistons being by a springdevice pressed against an inclined thrust collar, and said borings are connected via and an inlet valve with an inlet channel for a liquid pressure-medium and such borings are, via an outlet valve, connected with an outlet channel for the pressure-medium. The invention is characterised by the fact that the pump-block does not move, i. e. it does not rotate around the `driving shaft and the fact that both of the inclined thrust collars are supported by theV driving shaft and are rocked with the rotation of the shaft.

As the pump-block is Stationary, the construction of the piston pump is extremely simplified. As the axial pressure of the pistons is absorbed by the inclined thrust collars mounted on the driven shaft, the pump-block or thev pump-housing is not subjected to any axial stress. Further, the support of the shaft will be extremely simple. The dimensions of the pump can be made very small, but the eiciency of the pump is high. Only two small thrust inclined collars and two small shaft bearings are needed.

One construction of the pump can with advantage be used with a hydraulic driven press the clamping or operating device of which can be quickly adjusted into operative position before the press-operation itself takes place.

The clamping or operating device can be quickly adjusted, but the necessary force is normally not especially high. Therefore, a big mass of the pressure-medium, e. g. oil, is disposable for this purpose. For the pressoperation itself which very often is made by a relatively short movement of the pressing tool, a pressure-medium under high pressure is needed, whereas the mass of the pressing medium does not have to be very big. For this latter purpose, the pump-block is provided with an additional number of small borings or pump cylinders which are parallel to the driving shaft in which borings high pressure pistons are movable and which pistons are driven by the shaft via the inclined thrust collars. By means of such a pump a relatively big mass of the oil under low pressure or a relatively big mass of the oil under high pressure can be obtained and means may be provided for switching one output over to the other. The dimensions of the pump are small but the effect and the capacity of the pump are nevertheless great.

The inlet channel and the outlet channel for the pressure-medium can each be applied in a ring which rings surround the pump-housing or block which preferably is cylindrical, and according to a preferred embodiment of the invention the inlet channel, preferably co-axial to the driving shaft, can be applied in one of the bearing brackets 2,842,068 Fatented July 8, 1958 shaft is Figure 2 shows a cross section on the lines II-II of l Figure l.

Figure 3 shows a longitudinal section through the outer end of one of the pistons according to another embodiment of the invention.

Figure 4 shows an axial longitudinal sectional view` of a pump constructed with high pressure-pistons. p

Figure 5 shows a cross section on the lines V-V in Figure 4 of last mentioned pump.

A pump-block 1 comprises a boring 2 for a rotatably driven shaft 3. The pump-block is further provided with eight equally spaced borings or pump cylinders 4 around the boring 2 and parallel to the latter. In each of these borings 4 two axial movable pistons 5, 6 are provided with axial bores 7, in which bores 7 a helical spring 8 is inserted, which spring presses the pistons 5, 6 apart. At one end of the shaft 3 an inclined thrust collar 9 is applied, which collar is keyed to rotate with the shaft 3.

The collar 9 is provided with a face 11 inclined to the bearing 15 in a bearing bracket 17, fixed on the block t l by clevis pins 16. The bearing 15 is kept in its position by a stop nut i8, which is screwed on the shaft 3. Between the collar 9 and the innerring 19 of the ball bearing 15 a distance ring 20 is applied. At the opposite end of the shaft 3 is an inclined thrust collar 22 i fixed in a similar way by means of a key 2l which collar 22 has an oblique end face 23 facing the. oblique end face 11 of the collar 9. The outer ends of the pistons 6 are by their corresponding helical springs 8 pressed against the bearing ring 25 of the thrust bearing 24 which is mounted on the collar 22. The collars 9 and 22 are mounted on the shaft 3 in such a way that the two parts of them being closest to each other are at the bottom when the two parts being farthest away from each other are at the top (see Figure l). In order to prevent the collar 22 from being pushed to the right by the spring 8, a stop plate 27 is arranged in an annular groove 26 in the shaft 3, which plate 27 preferably can have the shape of a horseshoe. The right end of the shaft3 as per Figure l is carried by a `ball bearing 2S in the other bearing bracket 3l) which is fixed on the pump-block by clevis pins 29.

Around the block 1 which has a circular cross section two rings 31 and 32 are applied, each of them provided` with an annular channel 33 and 34 respectively both chan- The rings 31', 32, each" nels being open at their inner side. provided with an outlet connection piece 35, are kept in the desired position by a ring nut 36 which presses the Packing Y one of the borings 4. A nipple 42 is screwed into an extension 41 of the port 39. There is a seat 43 in the nipple 42. Against this seat 43 a ball 44 is tightly pressed by a helical spring 45. The inner end of the spring 45 rests on a transverse pin 46 in the nipple 42. In an extension 47 of the radial port 4i) is screwed a similar nipple 42 but reversely arranged to have the seat 43 at the inner end of the extension 47.

v14, 25 of the thrust bearings i3, 24.

aseaoes When the LVshaft 3 is rotating in either direction, the pistons 5, 6 at the upper part of pump as shown on the drawing are pressed apart by the spring and the pistons 5, 6 at the lower part of the pump are by the inner rings 14 and 25 of the thrust bearing 13, 24 and rocking thrust collars 9 and 22 axially pressed together against the action lof their springs 8. During the next half revolution of the shaft 3 the movements of the pistons 5, 6 will be reversed. When the pistons are pressed apart, the pressure-medium is `sucked from the inlet channel 33 through the inlet valve (the left nipple 42 in Figure l) in which the cali 44 against the action of the spring 45 leaves the seat 43. The pressurelmedium is further sucked through the port 39 into the boring 4. During the next half revolution of the shaft 3, when` these pistons are pressed towards each other, the pressure-medium is driven out of the boring 4 through the port 40 and the outlet valve (the right nipple 42 in Figure 1) out to the outlet channel 34. The pump is thus double-acting.

It is evident that the `axial pressure from the springs is absorbed only by the shaft 3 and it is thus not transmitted to the block 1. p

Figure l shows an embodiment of the invention, where the outer ends of the pistons 5, 6 are pressing directly against the rings 14, of the thrust bearings. A certain wearing at the ends of the pistons cannot be avoided, even if the pistons are made of hardened and ground steel. As Figure 3 shows, this wearing can be considerably reduced even if the pistons are not made of a very durable material. Figure 3 shows a construction where the outer end of the pistons (only one piston 5 is shown) are provided with a ball 4S, which ball is revolving in a spherical notch 49 in the outer end of the pistons. The ball 48 is provided with a liat Sti" which by a way of example can be made by grinding away a third of the ball 48. This fiat 50 of the ball 48 rests against the rings lt is thus evident that by means of this excellent carrying of the ball 48 in the notch 49 a relatively little wearing occurs during the working of the pump, especially as all the interior of the pump is lledwith oil. t

In Figures 4 and 5 showing thevpump with high pres sure pistons, the same reference numbers have been used for the details as for the corresponding details in the Figures l-3 (sometimes, however, index signs have also been used).

The pump block shown on the Figures 4 and 5 is pro` vided with ati-axial boring 2 for the shaft 3 and with eight borings or pump cylinders 4 parallel to this boring 2. Each of these borings 4 are at its centre closed by a distance piece 1a, dividing each of the borings into two coaxial borings 4 4and 4". ln each of these borings 4', 4 a piston S or 6 respectively is axially movable. Each of the'distance pieces la is provided with a small boring 4a, in which borings two well-fitted pistons 5c are axially movable. The outer end 5b of each of these pistons is formed as a head and arranged in an axial bore 7 in the pistons 5 and 6. The heads 5b are pressed against the closed end 7a of the pistons 5 and 6 by means of a spring 8a and 8b situated between an outer face of the distance piece 1a and the head 5b. These Springs 8a and 3b not only press the small pistons 5a apart but also the larger pistons 5, 6 are pressed apart. At one end of the shaft 3 is a collar 9 nonrotatably fixed thereon by means of a key and/ or a conical pin 10.

Around this block 1, which also has a circular cross section, four rings 50, 51, 52 and 53 are mounted, each of them provided with an annular channel 33 or 34 in'thc inner faces. Each of the rings 50, 51, 52 and 53 is provided with a connection piece 35, and the rings are kept in the desired position by means of a ring nut 36 pressing the rings against an annular rib 37 on the block 1. Between the block 1 and the rings Sti, 51, 52 and 53 are applied packing rings 38. Each of the channels 33 in the rings 50 and S3 communicates by a radial port 39 with ,4. each of the borings 4 and 4, and each of the channels 34 in the rings 51 and 52 communicates by means of radial ports 40a, 463]: with the boring 4a. ln an extension 41 in the port 39 a nipple 42 is screwed, in which a ball 44 is pressed against a seat 43 by means of a helical spring 45. In an extension 47 of the radial port 40a communicating with the channel A34 in the ring 51 a similar nipple 42 is screwed. Finally, also in an extension 47 in the port 49h which communicates with the channel 34 in the ring 52 is screwed a similar nipple 42, but rcversely arranged so that the seat 43 will be situated at the outer end of the extension 47.

The hub 3i) is provided with an axial inlet connection piece 54 for a pressure-medium. The pistons 5 and 6 are at their outer end provided with radial holes 55 through which the interior of the pump-block 1 (the boring 2) communicates with the bore 7 of the pistons 5, 6 when the latter are in their outer position (see the position of the lower pistons in Figure 4).

When the pistons, during the rotation of the shaft 3 in either direction, are in their outward position, the pressure-medium through the inlet connection piece 54 is sucked into the interior of the pump-block 1 and which pressure-medium via the boring 2 enters the bearing- 1oracket 17 is also sucked through the holes 55 in the pistons 5, 6 (see the position of the pistons at the foot of Figure 4) into the bore 7 in these pistons 5, 6. The suction of the pressure medium into these bores 7 takes place thanks to the negative pressure which is caused in the borings 4 and 4 when the pistons 5, 6 are pressed apart. The pistons 5, 6 thus operate as inlet valves. At the next half revolution of the shaft 3 when these two pistons 5, 6 are pressed towards each other, the pressure medium is driven out ofthe borings 4' and 4" through the ports 39 and the nor1-return outlet valves (the two outer nipples 42 on Figure 4) into the outlet channels 33.

When the pistons 6 are moving apart, the small pistons 5a are at the same time moving apart. When the pistons 5a are moving apart a negative pressure appears in the borings 4a, which causes the pressure-medium to be sucked from the channel 34 in the ring 52 via the non-return inlet valve (the nipples 4Z) situated at the inside of this ring and the ports 40a to the borings 4a. At the next half revolution of the shaft 3, when the same pistons 5a are pressed towards eachother, Vthe pressuremedium is driven out of the boring 4a through the port 4Gb and the channel 34 in the ring 51 via the outlet valves ywhich are situated inside this ring 51. The quantity of the pressure-medium pressed out through these valves. is less than the quantity of the pressure-medium pressed out through the channels 33 in the rings 5i) and 53, but on the other hand a higher pressure can be obtained on the first mentioned pressure-medium than on the last mentioned.

When loosening the nut 36 the rings 31, 32 or the rings 5t), 51, S2, 53 can be turned until their connection piece 35 is in its desired position whereupon the nut 36 is tightened again. This makes it possible to connect the pipes, leading the pressure-medium to and from the pump, at almost any position of the pump.

The illustrated and described embodiments of the invention are to be considered only as examples and the different parts of the pump can constructively be changed in many different ways without departing from the scope of the invention. For instance, the pistons 5a may be manufactured in one piece with the piston 5 or 6. Also the bearings absorbing the axial pressure from the pistons 5, 6 could be constructed in another way than shown on the drawings.

In order to make this description complete itrnust iinally be mentioned that the pump is intended to be connected with a pipe in a way that makes it possible for the pressuremedium from a receiver to he pressed back via an overtlow valve into the receiver when the working pressure during, for instance, the execution of the pressing operation raises over a certain value of the pressure which value is adjusted in advance. This overflow valve can preferably be applied at one end of a port in the block, which port via a check valve connects the ring channels 33 with one of the ring channels 34. Of course, the borings in the pump-block may be provided with linings of a durable material.

What I claim is:

1. A piston pump comprising, in combination, a stationary pump-block, a drive shaft rotatably mounted in said block, the latter having a plurality of borings arranged around the rotatable drive shaft, parallel to said shaft and extending through the block, pistons movable in opposite directions in said borings, springs for pressing the pistons apart, inclined thrust collars on said shaft, said pistons pressing against said collars and being reciprocated by the latter, one inlet valve and one inlet channel provided for each one of said borings and adapted for feeding liquid pressure medium to each one of the latter, one outlet valve being provided for each one of the borings and being connected with an outlet channel for delivering pressure medium from said borings, one wall of said inlet channel being composed of a ring surrounding said pump-block, and one wall of said outlet channel being composed of a similar ring arranged at the side of said first ring, each one of said rings being provided with an outlet connecting piece and kept in position by a ring nut tightly pressing said rings against an annular rib on said pump-block, said rings being turr1- able in relation to said pump-block.

2. In a device as claimed in claim 1, and wherein said inlet channel and said outlet channel are arranged as inwardly open, peripheral grooves in said rings surrounding said pump-block.

References Cited in the file of this patent UNITED STATES PATENTS 2,454,563 Mercier Nov. 23, 1948 2,492,688 Dall Dec. 27, 1949 2,540,328 Gray Feb. 6, 1951 2,633,802 Parilla et al. Apr. 7, 1953 2,709,339 Edelman et al.` May 31, 1955 2,722,890 Lucien Nov. 8, 1955 

